Reddish terrain colouring

[Mantock]

I'm fairly sure this issue ISN'T a problem with this terrain specifically. But I thought I'd post here because I know this is definitely not the colouring the terrain is supposed to be. And I'm wondering if anyone here knows what my issue might be. I've already gone through uninstalling Rex Accuseason Advanced to check if that was the problem. It's not. So I'm out of ideas. 

 

Anyone know why I've got this reddish tint to the terrain? It's fairly prevalent over southern England for me.